Japan launched an economic stimulus package worth more than 28 trillion yen (USD 266 billion) today, days before the central bank is expected to unveil its own growth-boosting measures.

Prime Minister Shinzo Abe announced the programme in a speech in southwestern Japan, giving few details except to say it would include about 13 trillion yen in fiscal measures including government spending.

More highlights of the package were expected next week when the cabinet is due to approve the measures announced in the city of Fukuoka.

Abe promised a stimulus package -- which earlier reports had varied at being worth 10 to 30 trillion yen -- after Britain's vote last month to quit the European Union sparked a rally in the yen that threatened profits at Japan Inc.

Traders tend to buy Japan's currency as a safe bet in times of turmoil or uncertainty. But it makes the country's exporters less competitive overseas and takes a bite out of their bottom line.

On currency markets, the dollar jumped as high as 106.54 yen from around 105.01 yen in the morning, after Fuji Television flagged the stimulus on Wednesday afternoon.

It was sitting at 105.54 yen after the announcement.

The news comes as speculation mounts that the Bank of Japan will further ease monetary policy after a two-day meeting Friday.

Since taking the helm more than three years ago BoJ governor Haruhiko Kuroda has overseen a massive asset-buying plan that now stands at an unprecedented 80 trillion yen annually.

The scheme is a cornerstone of Abe's push to beat years of deflation and kickstart growth, dubbed Abenomics.